Research Area: Cell fate regulation in epithelial tissue function and ageing
How epithelia coordinate cell and tissue structure with growth and metabolic activity to control morphogenesis and homeostasis of tissues is a fundamental question in biology. Altered regulation of epithelial cell/tissue architecture disturbs tissue homeostasis and promotes ageing and ageing-associated diseases, such as cancer and a range of inflammatory diseases. Using the self-renewing epidermis as a paradigm the Niessen laboratory asks how key regulators of the cyto-architecture control the formation and maintenance of epithelial tissues. More specifically, we ask how cell adhesion and polarity integrate with growth and inflammatory pathways to control stem cells, differentiation, tissue integrity and homeostasis in a stratifying epithelium, the epidermis of skin. Furthermore we ask if and how age-associated alterations in molecular regulators of cell architecture alter stem cell behavior and result in skin cancer and skin barrier related diseases.
All three projects depend on transgenic mouse models, most of which already exist in the lab or are in the process of being generated. Basic analysis of these lines includes histochemistry, immuno histochemistry and high resolution whole mount imaging. In close collaboration with the laboratory of Valentina Greco (Yale University), we have established non-invasive intravital microscopy (see e.g. Rompolas, Nature, 2012, 2013), which using different fluorescent mouse reporter lines enables revisiting the same stem cell populations within the epidermis. This technique will be used in all 3 projects. In the 3rd project we will also use in vivo imaging on embryos.
Another great advantage of using the epidermis as a paradigm for epithelial renewal and barrier function is not only the obvious ability to easily assess phenotypes but also the ability to isolate and culture epidermal keratinocytes. Projects will use these cultured cells from the different transgenic lines to assess biophysical (traction force and atomic force microscopy, cell stretching) and biochemical parameters and perform life cell imaging in 2d and 3d culture systems. All projects will also make use and /or take advantage of the fact that we have established SILAC and have and will perform proteomics and phospho- proteomics of cells and isolated epidermis of the different mouse models. Finally, when necessary we will perform RNA sequencing and ATAC sequencing to assess overall transcriptional changes and identify potential transcriptional regulators and motifs.